Most or many ships are equipped with at least one Radar system, used for navigation and/or other purposes. In particular, military vessels are frequently equipped with a weapons system Radar which is provided to locate, identify and possibly track possible threats. The complexity and functionality of such a weapons system Radar is far greater than that of a relatively simple navigational Radar system.
In typical prior art systems, the Radar antenna rotates to sweep signals across the location and is affixed to an upper portion of a high mast on the vessel. It is desirable to position the antenna as high as possible to give optimal range coverage and to avoid any other parts of the vessel from obscuring the transmit or receive Radar signal.
A problem with such an arrangement is that the antenna typically has a mass of several hundred kilograms. The mass of the system is due to prior art antennas incorporating a good deal of the Radio Frequency (RF) equipment within the antenna housing. Typically, this RF equipment includes one or more of transmitters, receivers, duplexers, filters and associated processing equipment.
The signals from the RF equipment are passed to digital processing systems, using one or more complex rotating joints which allow electrical continuity between the rotating antenna housing and the connected circuits.
Having a large, heavy rotating mass situated atop a mast, often at the highest point of the vessel, poses problems—not least in terms of stability, installation and maintenance—and there is a general desire to reduce the mass of the rotating part of the Radar system as far as possible. Prior art techniques have tended to concentrate on designing out as much mass from the RF equipment and housing, but there is a limit to how much mass can be eliminated from the antenna housing by these means.
Embodiments of the present invention aim to address these and other problems with prior art Radar antennas, whether mentioned herein or not.